金矿床定年方法进展及中国金矿成矿时代

金矿床定年方法进展及中国金矿成矿时代王义文（中国有色金属工业总公司吉林矿产地质研究所，长春１３００１２）关键词金矿床，中国金矿成矿时代，定年方法与金的独特地球化学性质有关，金矿成矿作用具有明显的层控性和继承性，即在矿源岩存在的前提下，多种成矿营力促使...

中国金矿床时空分布规律及地质背景

近年来,中国金矿地质勘查取得了较大的进展,一是大型或具有特大型资源潜力的矿床明显增多,首次发现了单个矿床资源量达到超大型的金矿床(如甘肃阳山、寨上,青海大场等);二是中西部地区或老矿区深部(隐伏)金矿找矿勘查工作取得重要突破(胶东焦家金矿)

中国金矿床类型、时空分布规律及找矿方向概述

在我国经济社会快速发展的过程中,对金矿开采技术水平提出了更高的要求.在此背景影响下,需要对我国金矿床类型、时空分布规律及找矿方向有着必要的了解,从而为后续相关生产计划的安全实施提供科学保障.基于此,本文就中国金矿床类型、时空分布规律及找矿方向展开论述.

中国金矿床时空分布特征

中国地处欧亚版块、太平洋板块和印度洋板块的交汇区,地质构造历史复杂,是全球少有的构造复杂地域。中国大陆地壳的固结时期晚,为非稳定型古陆,遭受后期活化的频率高,具有高度的活动性,形成了独特的时空分布特征。

中国红色粘土型金矿与国外红土型金矿的对比研究

红色粘土型金矿和红土型金矿都是风化壳型金矿,这两类金矿床多分布于热带—亚热带的温暖潮湿气候区。但是它们之间在构造环境、基岩岩性、风化壳型金矿体与原生矿关系、风化壳剖面、红土层的化学成分及金的赋存状态等方面存在着明显差异。因此,中国的这种风化壳型金矿不能硬套国外红土型金矿床的模式,称之为红色粘土金矿为宜。

为了闪光的事业

座落在海河之畔的冶金部天津地质研究院主要从事金属矿产地质研究和矿物材料应用开发研究工作。自1972年建院以来,不断拓宽地质科学研究的服务领域,在科研工作中密切结合生产实际,积极促进科研成果的转化。其中。

Distribution of Methyl Mercury in Rana chensinensis and Environmental Media in Gold-mining Areas of Upper Reaches of Songhua River,China

The distribution characteristics of methyl mercury in Rana chensinensis and water,sediment and soil in gold-mining areas of the upper reaches of the Songhua River,China were studied by field sampling and laboratory testing.The results show that the methyl mercury contents in water,sediment and soil in gold-mining areas are much higher than those in the control site,indicating that gold-mining activities intensify the methyl mercury pollution in the study area.Methyl mercury contents are in a descending order of sediment > soil > water in the environment,and in a descending order of brain > viscera > muscle > skin in Rana chensinensis.There are significant correlation between methyl mercury contents in Rana chensinensis and those in water and sediment.In particular,the methyl mercury content in the skin of Rana chensinensis is positively correlated with those in water and sediment in spring.Therefore,skin is one of main intake pathways for methyl mercury due to its high permeability.

Diversity of microbial community at acid mine drainages from Dachang metals-rich mine, China

Two acid mine drainage(AMD)samples TS and WK,which were from the Dachang metals-rich mine in Guangxi province,China,were studied using PCR-based cloning approach.A total of 44 operational taxonomic units(OTUs)were obtained from the two AMD samples.However,only three OTUs(GXDC-9,GXDC-19 and GXDC-50)detected in sample TS can also be observed in sample WK.Phylogenetic analysis revealed that the bacteria in the two samples fell into four putative divisions,which were Nitrospira,Alphaproteobacteria,Gamaproteobacteria,and Acidobacteria.Organisms of genuses Acidithiobacillus and Leptospirillum,which were in gamaproteobacteria class and Nitrospira family,were dominant in two samples,respectively.In sample TS,which was characterized by low pH,high sulfate,high iron,and high arsenide,two species(Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans)constituted 98.22% of the entire microbial community.Compared with sample TS,the microbial community in sample WK was more diversified according to the observation.Interestedly,the Legionella species,which was rarely observed in the low-pH environment,was detected in sample WK.This work helps us to further understand the diversity of microbial community living in extreme acid mine drainages with unique geochemistry and the tolerance capability of acidophiles to heavy metal.

Discipline progress of mineral mapping of gold deposit in China

Sanjiang and Jiaodong areas are the important gold regions in China.The gold mineralization is correlated with the Mesozoic faults and its derivative faults in the granite or the contact zone between granite and base rock.The mineral mapping is one of the important approaches of prospecting mineralogy.The temporal and spatial band distribution of mineral,mineral combination and mineral typomorphism features are natural regularity rules,but this kind of band feature is sometimes hidden and thus in need of mineral typomorphism research and mapping to disclose this band feature and to serve for the prospecting of mineral.The changes of the mineral typomorphism feature are often embodied in the"through"mineral,the typomorphism features of the through mineral change like the gradient toward the ore body,and the changes of the features are most obvious and strongest toward the orebodies.The new American mineralogy mapping indicates the weak change of the mineral composition or structure will lead to the change of the shape and wave length position of the specific absorbent feature.Australian experiment lab investigation has held the reason of a series of mineral.The progress achievement of the remote sensing and computer analysis technology now permits a direct comparison directly between the lab and remote sensing data,so the good feature database of the experiment light spectroscopy can serve for drawing of the spacial distribution and remote sensing material.Mineralogy mapping raised the extensive emphasis in the international earth arena.

Geochemistry of fluid inclusions from Linglong gold deposit in Shandong,China

By means of microscopy and laser Raman spectroscopy, the authors studied the fluid inclusions in petrography. The results show that there exist three-phase CO2-bearing and two-phase aqueous inclusions in gold ore; the fluid of NaC1-H2O-CO2 system went through immiscibility in ore-forming process. Ore-forming fluids were of low salinity （0. 82%- 5.40% NaCleqv）, low density （0. 54-0.93 g/cm3 ） ; mineralization temperature were concentrated in 320℃-340℃ , with ore-forming pressure in 62-126 MPa and mineralization depth in 6.34-9.35 kin. The fluid inclusions in quartz are generally characterized by a small amount of CO2 and Na. Combined with recent results of the isotopic analysis for fluid inclusions and dating data, it was indicated that the main ore-forming fluids derived mainly from source of mantle-derived fluids with a small amount of magmatic fluid and meteoric water. The genetic type was mesothermal gold deposits involved by mantle-derived fluids.

北京大学地质学系陈衍景副教授

随着科学研究的不断深入,各学科间相互交叉、渗透的发展趋势,已使跨学科的、有组织的社会化研究工作方式日显重要。“科学人”栏目的创办旨在促进各学科领域的科研工作者相互了解,增进交流与合作。

Late Mesozoic magmatism and tectonic evolution in the Southern margin of the North China Craton

Late Mesozoic granitic magmatism(158–112 Ma) are widespread in the southern margin of the North China Craton(NCC), contemporary with many world-class Mo-Au-Ag-Pb-Zn polymetallic deposits. There are abrupt changes in the elements and isotopic compositions of these granites at about 127 Ma. The early stage(158–128 Ma) granites show slightly or no negative Eu anomalies, large ion lithophile elements enriched and heavy REE depleted(such as Y and Yb), belonging to typical I-type granite. The late stage(126–112 Ma) granites are characterized by A-type and/or highly fractionated I-type granite, with higher contents of SiO2, K2 O, Y, Yb and Rb/Sr ratio and lower contents of Sr, δEu value and Sr/Y ratio than that of the early-stage granites.Moreover, the whole rock Nd and Hf isotopic compositions of the granites younger than 127 Ma show more depleted than those of the older one. The two stages of Late Mesozoic granites were derived from a source region of the ancient basement of the southern margin of the NCC incorporated the mantle material. The late stage(126–112 Ma) granites contain more fractions of mantle material with depleted isotopic composition than the early ones. The granites record evidence for a strong crust-mantle interaction. They formed in an intracontinental extensional setting which was related to lithospheric thinning and asthenospheric upwelling in this region, which was possibly caused by westward subduction of the Paleo-Pacific plate. 127 Ma is an critical period of the transformation of the tectonic regime.

Heavy metal content in scalp hair of the inhabitants near Dexing Copper Mine,Jiangxi Province,China

Levels of seven metals （Mn, Cu, Zn, Pb, Cr, Cd, and Se） in the scalp hair of Daicun and Xiangtian inhabitants were determined by ICP-MS/AFS. Daicun, as an experimental site, is near Dexing Copper Mine, Jiangxi Province, China, and exposed to mining pollution; Xiangtian, as a control site, is free from any mining and other industrial pollution. The heavy metal distribution in the scalp hair of the two diverse population segments exposed to different environments was discussed against the background of the heavy metal content of local plants, waters, and soils. The results show： 1） Levels ofCu, Zn, Pb, Cr, and Cd in the scalp hair of Daicun inhabitants were higher compared with Xiangtian counterparts which showed higher comparative levels of Se and Mn. But there were no significant differences of the levels of Cu and Zn in the hair samples between the two villages. In the hair of the inhabitants in the two villages, the levels for Se, Zn, and Cu were lower, while the level for Mn was higher, than the corresponding levels from other regions of the world. Compared with the standard issued by the Trace Element Research Council of China for Chinese inhabitants there were serious Se, Zn, Cu and Cr-deficiency phenomena in the hair samples from Daicun and Xiangtian. 2） Against the geological background of high levels ofZn, Cu, Se and Cr, there were deficiencies of Zn, Cu, Se and Cr in the hair samples of the Daictm population. This may have been caused by the distribution forms of the heavy metals in the soils, and antagonism among the elements. 3） Principal Component Analysis （PCA） and Cluster Analysis （CA） indicated that the origins of the heavy metals in the hair samples from the two villages had some differences as well as some similarities, this should be contributed mainly to the influence of the mining activities.

Evolution of the ductile shear zone of the Paishanlou gold deposits,western Liaoning,China

The combination of field surveys with analysis of microstructure of tectonite and Electron Backscatter Diffraction(EBSD) on quartz fabric indicated that three periods of ductile shear events developed in the Paishanlou gold deposits and the E-W and NE-striking ductile shear zones were formed during each event.The E-W-striking ductile shear zone,accompanied by compressional and dextral shear slip,was shear-cut by the NE-striking shear zones,accompanied by compressional-sinistral shear slip and sinistral-normal shear slip,successively.An E-W-striking ductile shear zone developed at a deeper tectonic level and at middle- to high-temperatures,accompanied by abundant microstructures,including microlayering between a polycrystal quartz belt and mica,and quartz deformation was depended on cylinder(10-10) or <c> glide.The development of an E-W-striking shear zone can be seen as a tectonic pattern in the region of the Paishanlou gold deposits of the collision between the Mongolian tectonic belt and the North Archean Craton from Suolun to the Linxi suture zone during the Indosinian.The NE-striking ductile shear zone developed approximately 160 Ma during the early Yianshanian at middle to shallow tectonic levels and at middle- to low-temperatures,accompanied by typical microstructures,including polycrystal quartz aggregation and quartz subgrain rotation recrystallization,etc.,and quartz deformation was depended on prismatic(1011) glide.The last ductile shear event around the NE-striking shear zone developed at low temperatures and shallow tectonic levels,yielding to a pre-existing NE-striking shear zone,accompanied by abundant microstructures,including low-temperature quartz grain boundary migration and bulging recrystallization.The last ductile shear movement may be related to lithosphere thinning and the destruction of the North China Craton from approximately 130-120 Ma,and this shear event resulted directly in the mineralization in the Paishanlou region.

Industrial structure optimization in central China under the energy constraint

Optimizing industrial structure is an important research object of human-economic geography, and it is also the object of government departments to strengthen macro-control. This has become even greater problem that China has entered the "new normal" in recent years. The study uses a multi-regional input-output model, with linear programming to build an optimal model of industrial structure as well as a model of optimization degree under the energy constraint. The results of the study revealed that:(1) the degree of optimization of industrial structure in Anhui Province is optimal(0.763), while that of Shanxi Province is the lowest(0.662);(2) the degree of optimization of industrial structure is negatively related to energy consumption per unit output value and the proportion of heavy industry; and(3) overall, central China should maintain or moderately increase the proportions of resource-based industry, greatly increase the proportions of manufacturing, including transport and telecommunications equipment, computers and other electronic equipment, and moderately reduce the proportions of smelting and pressing of metals and non-metal mineral products. In terms of service industries, the region should greatly increase the proportions of the production and supply of natural gas and tap water, moderately reduce or maintain the proportions of transport and storage as well as tourism, and maintain or moderately reduce the proportions of wholesale trade, retail trade and catering services.